Reaction Steps
In a dry 25 mL Schlenk-tube, which has been flooded with argon, complex 24b (58 mg, 0.05 mmol, 5 mol %) and MnCl2 (6.3 mg, 0.05 mmol) were dissolved in 1 mL of toluene. Subsequently, the mixture was heated for 30 to 80° C. and was re-cooled to room temperature. The solution of the catalyst was transferred into a suspension of 1-methoxy-2-(prop-1-inyl)benzene (325 mg, 1 mmol) and molecular sieve (1 g, 5 Å, powder) in 4 mL of toluene and the reaction mixture was stirred for 2 h at room temperature. Subsequently, it was filtered over a short silica gel column (2 cm), the filtrate was concentrated and the residue was purified by means of column chromatography (SiO2, hexane/EtOAc, 20:1). One obtains 1,2-bis(2-methoxyphenyl)ethine (116 mg, 97%) as colorless solid. M.p.=126-127° C.; 1H NMR (400 MHz, CD2Cl2): δ=7.49 (ddd, J=7.3, 1.6, 0.5 Hz, 2H), 7.33 (ddd, J=7.9, 7.7, 1.9 Hz, 2H), 6.95 (td, J=7.9, 1.0 Hz, 4H), 3.92 (s, 6H); 13C NMR (100 MHz, CD2Cl2): δ=160.3 (2×C), 133.7 (2×CH), 130.1 (2×CH), 120.8 (2×CH), 113.0 (2×C), 111.3 (2×CH), 90.1 (2×C), 56.2 (2×CH3); IR (film): v=3105, 3033, 2998, 2963, 2937, 2833, 1945, 1903, 1863, 1598, 1574, 1498, 1464, 1456, 1432, 1274, 1241, 1184, 1162, 1115, 1047, 1020, 937, 750 cm−1; MS (EI) m/z (%): 238 [M+] (100), 237 (32), 223 (23), 221 (15), 207 (10), 195 (5), 178 (8), 165 (14), 152 (9), 131 (19), 111 (6), 97 (3), 89 (3); HRMS (ESI): m/z: calculated for C16H14O2+Na: 261.0886. found: 261.0884.
